// Listing 16.9 Overloading operator<<()
#include <iostream>
#include <ostream>
#include <sstream>
#include <string.h>
#include <string>
using namespace std;

class String
{
    public:
        // constructors
        String();
        String(const char* const);
        String(const String&);
        ~String();

        // overloaded operators
        char &operator[](int offset);
        char operator[](int offset) const;
        String operator+(const String&);
        void operator+=(const String&);
        String &operator=(const String&);
        friend ostream& 
        operator<<(ostream& theStream, String& tehString);
        // General accessors
        int GetLen() const { return itsLen; }
        const char *GetString() const { return itsString; }
    private:
        String (int);    // private constructor
        char *itsString;
        unsigned short itsLen;
};

// default constructor creates string of 0 bytes
String::String()
{
    itsString = new char[1];
    itsString[0] = '\0';
    itsLen = 0;
    // cout << "\tDefault string constructor" << endl;
    // ConstructorCount++;
}

// private (helper) constructor, used only by 
// class methods for creating a new string of 
// required size. Null filled.
String::String(int len)
{
    itsString = new char[len + 1];
    for (int i = 0; i <= len; i++)
    {
        itsString[i] = '\0';
    }
    itsLen = len;
    // cout << "\tString(int) constructor" << endl;
    // ConstructorCount++;
}

// Converts a character array to a String
String::String(const char * const cString)
{
    itsLen = strlen(cString);
    itsString = new char[itsLen + 1];
    for (int i = 0; i < itsLen; i++)
    {
        itsString[i] = cString[i];
    }
    itsString[itsLen] = '\0';
    // cout << "\tString(char *) constructor" << endl;
    // ConstructorCount++;
}

// copy constructor
String::String(const String &rhs)
{
    itsLen = rhs.GetLen();
    itsString = new char[itsLen + 1];
    for (int i = 0; i < itsLen; i++)
    {
        itsString[i] = rhs[i];
    }
    itsString[itsLen] = '\0';
    // cout << "\tString(String&) constructor" << endl;
    // ConstructorCount++;
}

// destructor, frees allocated memory
String::~String()
{
    delete[] itsString;
    itsLen = 0;
    // cout << "\tString destructor" << endl;
}

// operator equals, freess existing memory
// then copies string and size
String& String::operator=(const String &rhs)
{
    if(this == &rhs)
    {
        return *this;
    }
    delete[] itsString;
    itsLen = rhs.GetLen();
    itsString = new char[itsLen + 1];
    for (int i = 0; i < itsLen; i++)
    {
        itsString[i] = rhs[i]; 
    }
    itsString[itsLen] = '\0';
    return *this;
    // cout << "\tString operator=" << endl;
}

// non constant offset operator, returns
// reference to character so it can be
// changed.
char &String::operator[](int offset)
{
    if(offset > itsLen)
    {
        return itsString[itsLen - 1];
    }
    else
    {
        return itsString[offset];
    }
}

// constant offset operator for use 
// on const objects (see copy constructor)
char String::operator[](int offset) const
{
    if(offset > itsLen)
    {
        return itsString[itsLen - 1];
    }
    else
    {
        return itsString[offset];
    }
}

// creates a new string by adding current
// string to rhs
String String::operator+(const String& rhs)
{
    int totalLen = itsLen + rhs.GetLen();
    String temp(totalLen);
    int i, j;
    for (i = 0; i < itsLen; i++)
    {
        temp[i] = itsString[i];
    }
    for(j = 0; j < rhs.GetLen(); j++, i++)
    {
        temp[i] = rhs[j];
    }
    temp[totalLen] = '\0';
    return temp;
}

// change current string, returns nothing
void String::operator+=(const String& rhs)
{
    unsigned short rhsLen = rhs.GetLen();
    unsigned short totalLen = itsLen + rhsLen;
    String temp(totalLen);
    int i, j;
    for (i = 0; i < itsLen; i++)
    {
        temp[i] = itsString[i];
    }

    for (j = 0, i = 0; j < rhs.GetLen(); j++, i++)
    {
        temp[i] = rhs[i - itsLen];
    }
    temp[totalLen] = '\0';
    *this = temp;
}

// int String::ConstructorCount=
ostream& operator<<(ostream& theStream, String& theString)
{
    theStream << theString.itsString;
    return theStream;
}

int main(void)
{
    String theString("Hello world");
    cout << theString;
}


